Hardware-accelerated crypto

The io-pkt-v4-hc and io-pkt-v6-hc managers have
the (hardware-independent) infrastructure
to load a (hardware-dependent) driver to take advantage of dedicated
hardware that can perform cryptographic operations at high speed.
This not only speeds up the crypto operations (such as those used by IPsec),
but also reduces the CPU load.

This interface is carefully crafted so that the stack doesn't block on
the crypto operation; rather, it continues, and later on, using a callback,
the driver returns the processed data to the stack.
This is ideal for DMA-driven crypto hardware.